Binding of Escherichia coli to fibronectin. A mechanism of tissue adherence

Four out of 17 enterotoxigenic strains of Escherichia coli isolated from infantile diarrhea bound ¹²⁵I-fibronectin. This binding, which was inhibited by unlabeled fibronectin but not by other proteins, appears to involve two classes of receptors, one of which binds the ligand reversibly. Consistent with the presence of two classes of receptors the bacteria bound to at least two distinct sites of the fibronectin molecule, one being the amino-terminal domain which also contains the binding sites for Gram-positive bacteria and the other located outside this domain. The E. coli strain expressing fibronectin receptors adhered to fibroblasts and to fibronectin but not to ovalbumin-coated coverslips. Bacteria grown at 40° C did not express fibronectin receptors and did not adhere to either substrate. Saturation of receptors with fibronectin blocked adhesion to both fibronectin-coated coverslips and to cultured fibroblasts. These data suggest that binding to fibronectin represents a mechanism of tissue adherence of E. coli.